transceiver: Remove remainings of the equalizer, restructure driveReceiveFIFO() for better modularity.

Equalizer has never worked properly and was always disabled. Now is a good time
to remove it completely to make the code cleaner.

Transceiver52M/Transceiver.cpp

@@ -50,9 +50,6 @@ TransceiverState::TransceiverState()
   for (int i = 0; i < 8; i++) {
     chanType[i] = Transceiver::NONE;
     fillerModulus[i] = 26;
-    chanResponse[i] = NULL;
-    DFEForward[i] = NULL;
-    DFEFeedback[i] = NULL;
 
     for (int n = 0; n < 102; n++)
       fillerTable[n][i] = NULL;
@@ -62,10 +59,6 @@ TransceiverState::TransceiverState()
 TransceiverState::~TransceiverState()
 {
   for (int i = 0; i < 8; i++) {
-    delete chanResponse[i];
-    delete DFEForward[i];
-    delete DFEFeedback[i];
-
     for (int n = 0; n < 102; n++)
       delete fillerTable[n][i];
   }
@@ -141,6 +134,12 @@ bool TransceiverState::init(int filler, size_t sps, float scale, size_t rtsc)
   return false;
 }
 
+void Transceiver::reset()
+{
+  for (size_t i = 0; i < mTxPriorityQueues.size(); i++)
+    mTxPriorityQueues[i].clear();
+}
+
 Transceiver::Transceiver(int wBasePort,
                          const char *wTRXAddress,
                          size_t wSPS, size_t wChans,
@@ -556,11 +555,9 @@ Transceiver::CorrType Transceiver::expectedCorrType(GSM::Time currTime,
 }
 
 /* 
- * Detect RACH synchronization sequence within a burst. No equalization
+ * Detect RACH synchronization sequence within a burst.
- * is used or available on the RACH channel.
  */
-int Transceiver::detectRACH(TransceiverState *state,
+int Transceiver::detectRACH(signalVector &burst,
-                            signalVector &burst,
                             complex &amp, float &toa)
 {
   float threshold = 6.0;
@@ -569,76 +566,16 @@ int Transceiver::detectRACH(TransceiverState *state,
 }
 
 /*
- * Detect normal burst training sequence midamble. Update equalization
+ * Detect normal burst training sequence midamble.
- * state information and channel estimate if necessary. Equalization
- * is currently disabled.
  */
-int Transceiver::detectTSC(TransceiverState *state, signalVector &burst,
+int Transceiver::detectTSC(signalVector &burst,
-                           complex &amp, float &toa, GSM::Time &time)
+                           complex &amp, float &toa)
 {
-  int success;
+  float threshold = 5.0;
-  int tn = time.TN();
-  float chanOffset, threshold = 5.0;
-  bool needDFE = false, estimateChan = false;
-  double elapsed = time - state->chanEstimateTime[tn];
-  signalVector *chanResp;
-
-  /* Check equalization update state */
-  if (needDFE && ((elapsed > 50) || (!state->chanResponse[tn]))) {
-    delete state->DFEForward[tn];
-    delete state->DFEFeedback[tn];
-    state->DFEForward[tn] = NULL;
-    state->DFEFeedback[tn] = NULL;
-
-    estimateChan = true;
-  }
 
   /* Detect normal burst midambles */
-  success = analyzeTrafficBurst(burst, mTSC, threshold, mSPSRx, amp,
+  return analyzeTrafficBurst(burst, mTSC, threshold, mSPSRx, amp,
-                                toa, mMaxExpectedDelay, estimateChan,
+                             toa, mMaxExpectedDelay);
-                                &chanResp, &chanOffset);
-  if (success <= 0) {
-    return success;
-  }
-
-  /* Set equalizer if unabled */
-  if (needDFE && estimateChan) {
-     float noise = state->mNoiseLev;
-     state->SNRestimate[tn] = amp.norm2() / (noise * noise + 1.0);
-
-     state->chanResponse[tn] = chanResp;
-     state->chanRespOffset[tn] = chanOffset;
-     state->chanRespAmplitude[tn] = amp;
-
-     scaleVector(*chanResp, complex(1.0, 0.0) / amp);
-
-     designDFE(*chanResp, state->SNRestimate[tn],
-               7, &state->DFEForward[tn], &state->DFEFeedback[tn]);
-
-     state->chanEstimateTime[tn] = time;
-  }
-
-  return 1;
-}
-
-/*
- * Demodulate GMSK burst using equalization if requested. Otherwise
- * demodulate by direct rotation and soft slicing.
- */
-SoftVector *Transceiver::demodulate(TransceiverState *state,
-                                    signalVector &burst, complex amp,
-                                    float toa, size_t tn, bool equalize)
-{
-  if (equalize) {
-    scaleVector(burst, complex(1.0, 0.0) / amp);
-    return equalizeBurst(burst,
-                         toa - state->chanRespOffset[tn],
-                         mSPSRx,
-                         *state->DFEForward[tn],
-                         *state->DFEFeedback[tn]);
-  }
-
-  return demodulateBurst(burst, mSPSRx, amp, toa);
 }
 
 void writeToFile(radioVector *radio_burst, size_t chan)
@@ -655,42 +592,47 @@ void writeToFile(radioVector *radio_burst, size_t chan)
  * Pull bursts from the FIFO and handle according to the slot
  * and burst correlation type. Equalzation is currently disabled. 
  */
-SoftVector *Transceiver::pullRadioVector(GSM::Time &wTime, double &RSSI, bool &isRssiValid,
+SoftVector *Transceiver::demodSignalVector(signalVector *burst,
-                                         double &timingOffset, double &noise,
+                                           CorrType type,
-                                         size_t chan)
+                                           double &timingOffset)
 {
   int success;
-  bool equalize = false;
   complex amp;
-  float toa, pow, max = -1.0, avg = 0.0;
+  float toa;
-  int max_i = -1;
-  signalVector *burst;
   SoftVector *bits = NULL;
-  TransceiverState *state = &mStates[chan];
-  isRssiValid = false;
 
-  /* Blocking FIFO read */
+  /* Detect normal or RACH bursts */
-  radioVector *radio_burst = mReceiveFIFO[chan]->read();
+  if (type == TSC)
-  if (!radio_burst)
+    success = detectTSC(*burst, amp, toa);
-    return NULL;
+  else
+    success = detectRACH(*burst, amp, toa);
 
-  /* Set time and determine correlation type */
+  /* Alert an error and exit */
-  GSM::Time time = radio_burst->getTime();
+  if (success <= 0) {
-  CorrType type = expectedCorrType(time, chan);
+    if (success == -SIGERR_CLIP) {
+      LOG(WARNING) << "Clipping detected on received RACH or Normal Burst";
+    } else if (success != SIGERR_NONE) {
+      LOG(WARNING) << "Unhandled RACH or Normal Burst detection error";
+    }
 
-  /* Debug: dump bursts to disk */
-  /* bits 0-7  - chan 0 timeslots
-   * bits 8-15 - chan 1 timeslots */
-  if (mWriteBurstToDiskMask & ((1<<time.TN()) << (8*chan)))
-    writeToFile(radio_burst, chan);
-
-  /* No processing if the timeslot is off.
-   * Not even power level or noise calculation. */
-  if (type == OFF) {
-    delete radio_burst;
     return NULL;
   }
 
+  timingOffset = toa / mSPSRx;
+
+  bits = demodulateBurst(*burst, mSPSRx, amp, toa);
+
+  return bits;
+}
+
+signalVector *Transceiver::chooseDiversityPath(radioVector *radio_burst, double &avg)
+{
+  signalVector *burst;
+  int max_i = -1;
+  float pow, max = -1.0;
+
+  avg = 0.0;
+
   /* Select the diversity channel with highest energy */
   for (size_t i = 0; i < radio_burst->chans(); i++) {
     energyDetect(*radio_burst->getVector(i), 20 * mSPSRx, 0.0, &pow);
@@ -703,7 +645,6 @@ SoftVector *Transceiver::pullRadioVector(GSM::Time &wTime, double &RSSI, bool &i
 
   if (max_i < 0) {
     LOG(ALERT) << "Received empty burst";
-    delete radio_burst;
     return NULL;
   }
 
@@ -711,62 +652,16 @@ SoftVector *Transceiver::pullRadioVector(GSM::Time &wTime, double &RSSI, bool &i
   burst = radio_burst->getVector(max_i);
   avg = sqrt(avg / radio_burst->chans());
 
-  wTime = time;
+  return burst;
-  RSSI = 20.0 * log10(rxFullScale / avg);
-
-  /* RSSI estimation are valid */
-  isRssiValid = true;
-
-  if (type == IDLE) {
-    /* Update noise levels */
-    state->mNoises.insert(avg);
-    state->mNoiseLev = state->mNoises.avg();
-    noise = 20.0 * log10(rxFullScale / state->mNoiseLev);
-
-    delete radio_burst;
-    return NULL;
-  } else {
-    /* Do not update noise levels */
-    noise = 20.0 * log10(rxFullScale / state->mNoiseLev);
-  }
-
-  /* Detect normal or RACH bursts */
-  if (type == TSC)
-    success = detectTSC(state, *burst, amp, toa, time);
-  else
-    success = detectRACH(state, *burst, amp, toa);
-
-  /* Alert an error and exit */
-  if (success <= 0) {
-    if (success == -SIGERR_CLIP) {
-      LOG(WARNING) << "Clipping detected on received RACH or Normal Burst";
-    } else if (success != SIGERR_NONE) {
-      LOG(WARNING) << "Unhandled RACH or Normal Burst detection error";
-    }
-
-    delete radio_burst;
-    return NULL;
-  }
-
-  timingOffset = toa / mSPSRx;
-
-  /* Demodulate and set output info */
-  if (equalize && (type != TSC))
-    equalize = false;
-
-  bits = demodulate(state, *burst, amp, toa, time.TN(), equalize);
-
-  delete radio_burst;
-  return bits;
 }
 
-void Transceiver::reset()
+void TransceiverState::updateNoiseEstimates(double avg)
 {
-  for (size_t i = 0; i < mTxPriorityQueues.size(); i++)
+  /* Update noise levels */
-    mTxPriorityQueues[i].clear();
+  mNoises.insert(avg);
+  mNoiseLev = mNoises.avg();
 }
 
-  
 void Transceiver::driveControl(size_t chan)
 {
   int MAX_PACKET_LENGTH = 100;
@@ -841,9 +736,8 @@ void Transceiver::driveControl(size_t chan)
   }
   else if (strcmp(command,"NOISELEV")==0) {
     if (mOn) {
-      float lev = mStates[chan].mNoiseLev;
       sprintf(response,"RSP NOISELEV 0 %d",
-              (int) round(20.0 * log10(rxFullScale / lev)));
+              (int) round(dB2(rxFullScale / mStates[chan].mNoiseLev)));
     }
     else {
       sprintf(response,"RSP NOISELEV 1  0");
@@ -980,20 +874,61 @@ void Transceiver::driveReceiveRadio()
 
 void Transceiver::driveReceiveFIFO(size_t chan)
 {
+  radioVector *radio_burst = NULL;
+  signalVector *burst = NULL;
   SoftVector *rxBurst = NULL;
+  double burst_power; // sqr(amp)
   double RSSI; // in dBFS
   double dBm;  // in dBm
   double TOA;  // in symbols
-  int TOAint;  // in 1/256 symbols
   double noise; // noise level in dBFS
   GSM::Time burstTime;
-  bool isRssiValid; // are RSSI, noise and burstTime valid
+  CorrType burstType;
 
-  rxBurst = pullRadioVector(burstTime, RSSI, isRssiValid, TOA, noise, chan);
+  /* Blocking FIFO read */
+  radio_burst = mReceiveFIFO[chan]->read();
+  if (!radio_burst)
+    return;
 
-  if (rxBurst) { 
+  /* Set time and determine correlation type */
+  burstTime = radio_burst->getTime();
+  burstType = expectedCorrType(burstTime, chan);
+
+  /* Debug: dump bursts to disk */
+  /* bits 0-7  - chan 0 timeslots
+   * bits 8-15 - chan 1 timeslots */
+  if (mWriteBurstToDiskMask & ((1<<burstTime.TN()) << (8*chan)))
+    writeToFile(radio_burst, chan);
+
+  /* No processing if the timeslot is off. */
+  if (burstType == OFF) {
+    delete radio_burst;
+    return;
+  }
+
+  /* Choose a diversity channel to use */
+  burst = chooseDiversityPath(radio_burst, burst_power);
+  delete radio_burst;
+  if (!burst) {
+    return;
+  }
+
+  /* We use idle timeslots to calculate noise levels for informational purposes.
+   * Otherwise we ignore them. */
+  if (burstType == IDLE) {
+    mStates[chan].updateNoiseEstimates(burst_power);
+    return;
+  }
+
+  /* Update/calculate burst info */
+  noise = dB2(rxFullScale / mStates[chan].mNoiseLev);
+  RSSI  = dB2(rxFullScale / burst_power);
   dBm   = RSSI+rssiOffset;
-    TOAint = (int) (TOA * 256.0 + 0.5); // round to closest integer
+
+  /* Pre-process and demodulate radio vector */
+  rxBurst = demodSignalVector(burst, burstType, TOA);
+  if (!rxBurst)
+    return;
 
   LOG(DEBUG) << std::fixed << std::right
     << " time: "   << burstTime
@@ -1003,6 +938,18 @@ void Transceiver::driveReceiveFIFO(size_t chan)
     << " bits: "   << *rxBurst;
 
   char burstString[gSlotLen+10];
+  formatDemodPacket(burstTime, dBm, TOA, rxBurst, burstString);
+  delete rxBurst;
+
+  mDataSockets[chan]->write(burstString,gSlotLen+10);
+}
+
+void Transceiver::formatDemodPacket(GSM::Time burstTime, double dBm, double TOA,
+                                    SoftVector *rxBurst, char *burstString)
+{
+  int TOAint;  // in 1/256 symbols
+  TOAint = (int) (TOA * 256.0 + 0.5); // round to closest integer
+
   burstString[0] = burstTime.TN();
   for (int i = 0; i < 4; i++)
     burstString[1+i] = (burstTime.FN() >> ((3-i)*8)) & 0x0ff;
@@ -1015,10 +962,6 @@ void Transceiver::driveReceiveFIFO(size_t chan)
     burstString[8+i] =(char) round((*burstItr++)*255.0);
   }
   burstString[gSlotLen+9] = '\0';
-    delete rxBurst;
-
-    mDataSockets[chan]->write(burstString,gSlotLen+10);
-  }
 }
 
 void Transceiver::driveTxFIFO()

Transceiver52M/Transceiver.h

@@ -55,29 +55,15 @@ struct TransceiverState {
 
   /* Initialize a multiframe slot in the filler table */
   bool init(int filler, size_t sps, float scale, size_t rtsc);
+  void updateNoiseEstimates(double avg);
 
   int chanType[8];
 
-  /* Last timestamp of each timeslot's channel estimate */
-  GSM::Time chanEstimateTime[8];
-
   /* The filler table */
   signalVector *fillerTable[102][8];
   int fillerModulus[8];
   bool mRetrans;
 
-  /* Most recent channel estimate of all timeslots */
-  signalVector *chanResponse[8];
-
-  /* Most recent DFE feedback filter of all timeslots */
-  signalVector *DFEForward[8];
-  signalVector *DFEFeedback[8];
-
-  /* Most recent SNR, timing, and channel amplitude estimates */
-  float SNRestimate[8];
-  float chanRespOffset[8];
-  complex chanRespAmplitude[8];
-
   /* Received noise energy levels */
   float mNoiseLev;
   noiseVector mNoises;
@@ -195,9 +181,15 @@ private:
   void pushRadioVector(GSM::Time &nowTime);
 
   /** Pull and demodulate a burst from the receive FIFO */
-  SoftVector *pullRadioVector(GSM::Time &wTime, double &RSSI, bool &isRssiValid,
+  SoftVector *demodSignalVector(signalVector *burst,
-                              double &timingOffset, double &noise,
+                                CorrType type,
-                              size_t chan = 0);
+                                double &timingOffset);
+
+  /** choose the channel to use */
+  signalVector *chooseDiversityPath(radioVector *radio_burst, double &avg);
+
+  /** update noise estimate */
+  double updateNoiseEstimates(TransceiverState *state, double avg);
 
   /** Set modulus for specific timeslot */
   void setModulus(size_t timeslot, size_t chan);
@@ -209,19 +201,12 @@ private:
   void writeClockInterface(void);
 
   /** Detect RACH bursts */
-  int detectRACH(TransceiverState *state,
+  int detectRACH(signalVector &burst,
-                 signalVector &burst,
                  complex &amp, float &toa);
 
   /** Detect normal bursts */
-  int detectTSC(TransceiverState *state,
+  int detectTSC(signalVector &burst,
-                signalVector &burst,
+                complex &amp, float &toa);
-                complex &amp, float &toa, GSM::Time &time);
-
-  /** Demodulat burst and output soft bits */
-  SoftVector *demodulate(TransceiverState *state,
-                         signalVector &burst, complex amp,
-                         float toa, size_t tn, bool equalize);
 
   int mSPSTx;                          ///< number of samples per Tx symbol
   int mSPSRx;                          ///< number of samples per Rx symbol
@@ -251,6 +236,10 @@ protected:
   /** drive demodulation of GSM bursts */
   void driveReceiveFIFO(size_t chan);
 
+  /** format a packet of soft-bits to be sent over the network */
+  void formatDemodPacket(GSM::Time burstTime, double dBm, double TOA,
+                         SoftVector *rxBurst, char *burstString);
+
   /** drive transmission of GSM bursts */
   void driveTxFIFO();
 

Transceiver52M/sigProcLib.cpp

@@ -147,64 +147,8 @@ void sigProcLibDestroy()
   GSMPulse1 = NULL;
 }
 
-// dB relative to 1.0.
+double dB2(double x) {
-// if > 1.0, then return 0 dB
+  return 20.0 * log10(x);
-float dB(float x) {
-  
-  float arg = 1.0F;
-  float dB = 0.0F;
-  
-  if (x >= 1.0F) return 0.0F;
-  if (x <= 0.0F) return -200.0F;
-
-  float prevArg = arg;
-  float prevdB = dB;
-  float stepSize = 16.0F;
-  float dBstepSize = 12.0F;
-  while (stepSize > 1.0F) {
-    do {
-      prevArg = arg;
-      prevdB = dB;
-      arg /= stepSize;
-      dB -= dBstepSize;
-    } while (arg > x);
-    arg = prevArg;
-    dB = prevdB;
-    stepSize *= 0.5F;
-    dBstepSize -= 3.0F;
-  }
- return ((arg-x)*(dB-3.0F) + (x-arg*0.5F)*dB)/(arg - arg*0.5F);
-
-}
-
-// 10^(-dB/10), inverse of dB func.
-float dBinv(float x) {
-  
-  float arg = 1.0F;
-  float dB = 0.0F;
-  
-  if (x >= 0.0F) return 1.0F;
-  if (x <= -200.0F) return 0.0F;
-
-  float prevArg = arg;
-  float prevdB = dB;
-  float stepSize = 16.0F;
-  float dBstepSize = 12.0F;
-  while (stepSize > 1.0F) {
-    do {
-      prevArg = arg;
-      prevdB = dB;
-      arg /= stepSize;
-      dB -= dBstepSize;
-    } while (dB > x);
-    arg = prevArg;
-    dB = prevdB;
-    stepSize *= 0.5F;
-    dBstepSize -= 3.0F;
-  }
-
-  return ((dB-x)*(arg*0.5F)+(x-(dB-3.0F))*(arg))/3.0F;
-
 }
 
 float vectorNorm2(const signalVector &x) 
@@ -1478,8 +1422,7 @@ int detectRACHBurst(signalVector &rxBurst,
  *   tail: Search 4 symbols + maximum expected delay
  */
 int analyzeTrafficBurst(signalVector &rxBurst, unsigned tsc, float thresh,
-                        int sps, complex &amp, float &toa, unsigned max_toa,
+                        int sps, complex &amp, float &toa, unsigned max_toa)
-                        bool chan_req, signalVector **chan, float *chan_offset)
 {
   int rc, target, head, tail;
   CorrelationSequence *sync;
@@ -1495,14 +1438,6 @@ int analyzeTrafficBurst(signalVector &rxBurst, unsigned tsc, float thresh,
   rc = detectGeneralBurst(rxBurst, thresh, sps, amp, toa,
                           target, head, tail, sync);
 
-  /* Equalization not currently supported */
-  if (rc > 0 && chan_req) {
-    *chan = new signalVector(6 * sps);
-
-    if (chan_offset)
-      *chan_offset = 0.0;
-  }
-
   return rc;
 }
 
@@ -1559,166 +1494,6 @@ SoftVector *demodulateBurst(signalVector &rxBurst, int sps,
   return bits;
 }
 
-// Assumes symbol-spaced sampling!!!
-// Based upon paper by Al-Dhahir and Cioffi
-bool designDFE(signalVector &channelResponse,
-	       float SNRestimate,
-	       int Nf,
-	       signalVector **feedForwardFilter,
-	       signalVector **feedbackFilter)
-{
-  
-  signalVector G0(Nf);
-  signalVector G1(Nf);
-  signalVector::iterator G0ptr = G0.begin();
-  signalVector::iterator G1ptr = G1.begin();
-  signalVector::iterator chanPtr = channelResponse.begin();
-
-  int nu = channelResponse.size()-1;
-
-  *G0ptr = 1.0/sqrtf(SNRestimate);
-  for(int j = 0; j <= nu; j++) {
-    *G1ptr = chanPtr->conj();
-    G1ptr++; chanPtr++;
-  }
-
-  signalVector *L[Nf];
-  signalVector::iterator Lptr;
-  float d = 1.0;
-  for(int i = 0; i < Nf; i++) {
-    d = G0.begin()->norm2() + G1.begin()->norm2();
-    L[i] = new signalVector(Nf+nu);
-    Lptr = L[i]->begin()+i;
-    G0ptr = G0.begin(); G1ptr = G1.begin();
-    while ((G0ptr < G0.end()) &&  (Lptr < L[i]->end())) {
-      *Lptr = (*G0ptr*(G0.begin()->conj()) + *G1ptr*(G1.begin()->conj()) )/d;
-      Lptr++;
-      G0ptr++;
-      G1ptr++;
-    }
-    complex k = (*G1.begin())/(*G0.begin());
-
-    if (i != Nf-1) {
-      signalVector G0new = G1;
-      scaleVector(G0new,k.conj());
-      addVector(G0new,G0);
-
-      signalVector G1new = G0;
-      scaleVector(G1new,k*(-1.0));
-      addVector(G1new,G1);
-      delayVector(&G1new, &G1new, -1.0);
-
-      scaleVector(G0new,1.0/sqrtf(1.0+k.norm2()));
-      scaleVector(G1new,1.0/sqrtf(1.0+k.norm2()));
-      G0 = G0new;
-      G1 = G1new;
-    }
-  }
-
-  *feedbackFilter = new signalVector(nu);
-  L[Nf-1]->segmentCopyTo(**feedbackFilter,Nf,nu);
-  scaleVector(**feedbackFilter,(complex) -1.0);
-  conjugateVector(**feedbackFilter);
-
-  signalVector v(Nf);
-  signalVector::iterator vStart = v.begin();
-  signalVector::iterator vPtr;
-  *(vStart+Nf-1) = (complex) 1.0;
-  for(int k = Nf-2; k >= 0; k--) {
-    Lptr = L[k]->begin()+k+1;
-    vPtr = vStart + k+1;
-    complex v_k = 0.0;
-    for (int j = k+1; j < Nf; j++) {
-      v_k -= (*vPtr)*(*Lptr);
-      vPtr++; Lptr++;
-    }
-     *(vStart + k) = v_k;
-  }
-
-  *feedForwardFilter = new signalVector(Nf);
-  signalVector::iterator w = (*feedForwardFilter)->end();
-  for (int i = 0; i < Nf; i++) {
-    delete L[i];
-    complex w_i = 0.0;
-    int endPt = ( nu < (Nf-1-i) ) ? nu : (Nf-1-i);
-    vPtr = vStart+i;
-    chanPtr = channelResponse.begin();
-    for (int k = 0; k < endPt+1; k++) {
-      w_i += (*vPtr)*(chanPtr->conj());
-      vPtr++; chanPtr++;
-    }
-    *--w = w_i/d;
-  }
-
-
-  return true;
-  
-}
-
-// Assumes symbol-rate sampling!!!!
-SoftVector *equalizeBurst(signalVector &rxBurst,
-		       float TOA,
-		       int sps,
-		       signalVector &w, // feedforward filter
-		       signalVector &b) // feedback filter
-{
-  signalVector *postForwardFull;
-
-  if (!delayVector(&rxBurst, &rxBurst, -TOA))
-    return NULL;
-
-  postForwardFull = convolve(&rxBurst, &w, NULL,
-                             CUSTOM, 0, rxBurst.size() + w.size() - 1);
-  if (!postForwardFull)
-    return NULL;
-
-  signalVector* postForward = new signalVector(rxBurst.size());
-  postForwardFull->segmentCopyTo(*postForward,w.size()-1,rxBurst.size());
-  delete postForwardFull;
-
-  signalVector::iterator dPtr = postForward->begin();
-  signalVector::iterator dBackPtr;
-  signalVector::iterator rotPtr = GMSKRotationN->begin();
-  signalVector::iterator revRotPtr = GMSKReverseRotationN->begin();
-
-  signalVector *DFEoutput = new signalVector(postForward->size());
-  signalVector::iterator DFEItr = DFEoutput->begin();
-
-  // NOTE: can insert the midamble and/or use midamble to estimate BER
-  for (; dPtr < postForward->end(); dPtr++) {
-    dBackPtr = dPtr-1;
-    signalVector::iterator bPtr = b.begin();
-    while ( (bPtr < b.end()) && (dBackPtr >= postForward->begin()) ) {
-      *dPtr = *dPtr + (*bPtr)*(*dBackPtr);
-      bPtr++;
-      dBackPtr--;
-    }
-    *dPtr = *dPtr * (*revRotPtr);
-    *DFEItr = *dPtr;
-    // make decision on symbol
-    *dPtr = (dPtr->real() > 0.0) ? 1.0 : -1.0;
-    //*DFEItr = *dPtr;
-    *dPtr = *dPtr * (*rotPtr);
-    DFEItr++;
-    rotPtr++;
-    revRotPtr++;
-  }
-
-  vectorSlicer(DFEoutput);
-
-  SoftVector *burstBits = new SoftVector(postForward->size());
-  SoftVector::iterator burstItr = burstBits->begin();
-  DFEItr = DFEoutput->begin();
-  for (; DFEItr < DFEoutput->end(); DFEItr++) 
-    *burstItr++ = DFEItr->real();
-
-  delete postForward;
-
-  delete DFEoutput;
-
-  return burstBits;
-}
-
 bool sigProcLibSetup(int sps)
 {
   if ((sps != 1) && (sps != 4))

Transceiver52M/sigProcLib.h

@@ -36,8 +36,8 @@ enum signalError {
   SIGERR_INTERNAL,
 };
 
-/** Convert a linear number to a dB value */
+/** Convert a power value to a dB value */
-float dB(float x);
+double dB2(double x);
 
 /** Convert a dB value into a linear value */
 float dBinv(float x);
@@ -204,9 +204,6 @@ int detectRACHBurst(signalVector &rxBurst,
         @param amplitude The estimated amplitude of received TSC burst.
         @param TOA The estimate time-of-arrival of received TSC burst.
         @param maxTOA The maximum expected time-of-arrival
-        @param requestChannel Set to true if channel estimation is desired.
-        @param channelResponse The estimated channel.
-        @param channelResponseOffset The time offset b/w the first sample of the channel response and the reported TOA.
         @return positive if threshold value is reached, negative on error, zero otherwise
 */
 int analyzeTrafficBurst(signalVector &rxBurst,
@@ -215,10 +212,7 @@ int analyzeTrafficBurst(signalVector &rxBurst,
                         int sps,
                         complex &amplitude,
                         float &TOA,
-                        unsigned maxTOA,
+                        unsigned maxTOA);
-                        bool requestChannel = false,
-                        signalVector** channelResponse = NULL,
-                        float *channelResponseOffset = NULL);
 
 /**
 	Decimate a vector.
@@ -240,34 +234,4 @@ signalVector *decimateVector(signalVector &wVector, size_t factor);
 SoftVector *demodulateBurst(signalVector &rxBurst, int sps,
                             complex channel, float TOA);
 
-/**
-	Design the necessary filters for a decision-feedback equalizer.
-	@param channelResponse The multipath channel that we're mitigating.
-	@param SNRestimate The signal-to-noise estimate of the channel, a linear value
-	@param Nf The number of taps in the feedforward filter.
-	@param feedForwardFilter The designed feed forward filter.
-	@param feedbackFilter The designed feedback filter.
-	@return True if DFE can be designed.
-*/
-bool designDFE(signalVector &channelResponse,
-	       float SNRestimate,
-	       int Nf,
-	       signalVector **feedForwardFilter,
-	       signalVector **feedbackFilter);
-
-/**
-	Equalize/demodulate a received burst via a decision-feedback equalizer.
-	@param rxBurst The received burst to be demodulated.
-	@param TOA The time-of-arrival of the received burst.
-	@param sps The number of samples per GSM symbol.
-	@param w The feed forward filter of the DFE.
-	@param b The feedback filter of the DFE.
-	@return The demodulated bit sequence.
-*/
-SoftVector *equalizeBurst(signalVector &rxBurst,
-		       float TOA,
-		       int sps,
-		       signalVector &w, 
-		       signalVector &b);
-
 #endif /* SIGPROCLIB_H */